Catheter apparatus with weeping tip and method of use

ABSTRACT

The invention provides surgical needles with a porous distal portion from which a liquid injectate will weep or ooze multidirectionally under injection pressure while the porous distal portion of the needle is inserted into a body surface. The porous distal portion of the needle can be fabricated from a porous carbon, metal, ceramic or polymer and preferably has a decreasing gradient of impedance to fluid flowing to the point of the needle to compensate for the falling off of injection pressure as fluid moves towards the point, thereby ensuring uniform weeping of the injectate along the injection course. The needle is adapted for attachment to a catheter or syringe. In another embodiment, a surgical assemblage is provided wherein a porous distal portion having similar fluid flow characteristics is located along the distal end of a catheter, and a needle point is attached to the distal end of the catheter (e.g., a steerable catheter) for piercing tissue. A guidance catheter can be used to direct the invention devices to a remote internal injection site. The invention devices and methods can be used to inject fluids (including those containing nucleic acids for gene therapy) into interior body walls or tissue, such as a beating heart, without substantial loss of fluid and without substantial damage to tissue caused by injectate.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.09/468,688, filed Dec. 20, 1999, now U.S. Pat. No. 6,241,710 issued Jun.5, 2001, entitled “HYPODERMIC NEEDLE WITH WEEPING TIP AND METHOD OFUSE.”

FIELD OF THE INVENTION

The present invention generally relates to surgical instruments and toinstruments used to inject medicaments into a body wall or tissue.

BACKGROUND OF THE INVENTION

The direct introduction of a drug, compound, biologically active peptideor protein into the cells of a patient can have significant therapeuticvalue. However, this approach also has several drawbacks. Of primaryconcern is the risk of potential toxicity, particularly at dosagessufficient to produce a biological response to the peptide. From apractical perspective, there is also the problem of the cost associatedwith isolating and purifying or synthesizing the peptides. Moreover, theclinical impact of the peptides is also limited by their relativelyshort half-life in vivo, which usually results from their degradation byany proteases present in the target tissue.

For these reasons, introduction of bioactive agents, including proteins,into a patient by delivery of a gene or a cell containing a gene thatwill express a therapeutic protein in the patient/host is an intriguingalternative to administering the substance. However, to date theprincipal means for introduction of foreign genetic material into a hosthas involved the integration of the gene into the host genome by, forexample, transforming the host's cells with a viral vector. Direct invivo gene transfer into postnatal animals has also been reported usingDNA encapsulated in liposomes including DNA entrapped in proteoliposomescontaining viral envelope receptor proteins.

With respect to delivery systems for genes, means such as viral vectorswhich introduce the gene into the host's genome can present potentialhealth risks associated with damage to the genetic material in the hostcell. Use of cationic liposomes or a biolistic device (i.e., a vaccine“gun” which “shoots” polynucleotides coupled to beads into tissue) todeliver genes in vivo is preparation intensive and, in some cases,requires some experimentation to select proper particle sizes fortransmission into target cells. Further, any invasive means ofintroducing nucleotides (e.g., injection) poses problems of tissuetrauma (particularly in long-term therapies) and presents limited accessto certain target tissues, such as organs.

Means for non-invasive delivery of pharmaceutical preparations ofpeptides, such as iontophoresis and other means for transdermaltransmission, have the advantage of minimizing tissue trauma. However,it is believed that the bioavailability of peptides followingtransdermal or mucosal transmission is limited by the relatively highconcentration of proteases in these tissues.

Injection of “naked DNA” directly into muscle has also been investigatedat length. In 1984, work at the NIH was reported which showed thatintrahepatic injection of naked, cloned plasmid DNA for squirrelhepatitis into squirrels produced both viral infection and the formationof antiviral antibodies in the squirrels (Seeger, et al,Proc.Nat'l.Acad.Sci USA, 81:5849-5852, 1984). Several years later,Felgner, et al., reported that they obtained expression of protein from“naked” polynucleotides (i.e., DNA or RNA not associated with liposomesor a viral expression vector) injected into skeletal muscle tissue(Felgner, et al., Science, 247:1465, 1990; see also, PCT application WO90/11092). Feigner, et al. surmised that muscle cells efficiently takeup and express polynucleotides because of the unique structure of muscletissue, which is comprised of multinucleated cells, sarcoplasmicreticulum and a transverse tubular system which extends deep into themuscle cell.

Today, injection of heterologous nucleic acid into cells of striatedmuscle is generally considered effective to cause expression of DNA orRNA injected into the cells. Gene transfer by injection into subjects oflive cells containing nucleic acids that will express therapeutic genesin vivo is also greatly desired, particularly for treatment siteslocated within a body cavity that can be reached in a relativelynon-invasive manner by the use of a catheter. However, gene transfer byinjection of nucleic acid or cells containing therapeutic genes iscomplicated when the injection site is both remote (i.e., located withina body cavity) and in motion. A particularly difficult target for suchtherapeutic techniques is a beating heart and associated arterialtissue.

Further, even though the amount of the particular isolated therapeuticgenes or cells injected into a patient is small, the costs involved inpreparation of such therapeutic substances is high. Therefore, anyinjectate lost during transfer to the patient, for example, by leakagedue to too rapid a transfer, represents a considerable monetary loss.

Accordingly, there is still a need in the art for new and better needlesand injection systems or surgical assemblages suitable formicroinjection of controlled amounts of therapeutic substances withoutsubstantial loss of injectate and without substantial damage to tissue,even upon repeat injections. There is a particular need for needles thatare adapted for attachment to various types of catheters for suchcontrolled delivery of therapeutic substances at remote locations withinthe body.

BRIEF DESCRIPTION OF THE INVENTION

The present invention overcomes many of the problems in the art byproviding a surgical needle with a weeping tip for microinjection ofmedicaments into a body surface. The invention surgical needle comprisesa nonporous hollow needle shaft having a proximal end adapted to matewith a surgical instrument, a porous distal portion in fluid-tightconnection to the needle shaft, and a point that is open, closed or hasa solid partial plug. The porous distal portion of the invention needleis adapted to cause a liquid injectate to weep or ooze therefrommultidirectionally under injection pressure while the distal portion andpoint of the needle are inserted into a body surface. Preferably, theinvention needle has features that create a substantially uniform rateof weeping of injectate along the length of the porous distal portionthereof.

The invention surgical needle with weeping tip can be adapted forattachment to such surgical instruments as a syringe, but is preferablyadapted for attachment to the distal tip of a catheter.

In another embodiment according to the present invention, there areprovided surgical assemblage(s) useful for injecting a liquid medicamentinto a remote location in a subject in need thereof. The inventionsurgical assemblage comprises a needle with a sharp distal point with orwithout flow-through, and a catheter with a porous distal portion (suchas a porous polymer) attached to the distal end of the needle, whereinthe porous distal portion of the catheter is adapted to cause a liquidinjectate to weep or ooze multidirectionally therefrom into surroundingtissue under injection pressure while inserted into a body surface. Theremainder of the catheter is nonporous to assure that the medicamentwill be delivered only to tissue in contact with the porous portion ofthe catheter.

The invention surgical needle and/or surgical assemblage is ideallysuited for injection into tissue of medicaments containing nucleic acidencoding a therapeutic agent (or cells containing such nucleic acid).For example, the invention needle (when attached to an appropriatecatheter) or invention surgical assemblage can be used to injectmedicament(s) into the wall of a beating heart or other internal organ,without substantial loss of the medicament at the surface of the bodywall and without substantial damage to tissue at the injection sitecaused by injectate.

Accordingly, in another embodiment according to the present invention,there are provided methods for injecting a medicament into tissue in asubject in need thereof. The invention injection method comprisesinserting the distal portion of the invention needle into the tissue ofthe subject and causing a therapeutic amount of the medicament to oozemultidirectionally from the needle into the tissue without substantialleakage or loss of the medicament at the surface of the tissue. Theinvention method using the invention needle (or surgical assemblage)with porous distal portion is designed for injection of minute amountsof fluid into tissue or a body wall, hence the use of the term“microinjection” herein.

In another embodiment according to the present invention, there areprovided methods for injecting a medicament into a subject in needthereof comprising inserting the distal portion of the invention needleinto an interior body wall or tissue of the subject and applyingsufficient pressure to a liquid medicament in fluid communication withthe distal portion of the needle to expel the medicament such that themedicament weeps multidirectionally from the pores in the distal portionthereof into the interior body wall or tissue without substantialleakage or loss of the medicament at the surface of the body wall. Theinvention methods are particularly useful for injecting medicament(s)into an interior body wall or tissue that is subject to motion, forexample, the wall of a beating heart during electrophysiologic testing,transmyocardial revascularization, and the like.

In yet another embodiment, the present invention provides a method forinjecting a medicament into tissue in a subject in need thereofcomprising: inserting the distal portion of an invention needle into thetissue of the subject and causing a therapeutic amount of the medicamentto ooze multidirectionally from the needle into the tissue withoutsubstantial damage to the tissue of the subject caused by injectate.

It is a particular object of the present invention to provide devicesand methods useful for simultaneously injecting a medicament frommultiple orifices along an injection course, rather than delivering abolus injection, as is the case with traditional hypodermic needles.

BRIEF DESCRIPTION OF THE FIGURE

FIG. 1 is a schematic drawing showing an exploded view of the inventionneedle with weeping tip and a catheter to which it attaches.

FIG. 2 is a schematic drawing showing the invention needle with theelectrical connector for attachment to an electrocardiogram.

FIG. 3 is a schematic drawing showing the invention surgical assemblagecomprising a catheter and a needle, wherein the porous distal portion islocated in the flexible catheter.

DETAILED DESCRIPTION OF THE INVENTION

The present invention overcomes many of the problems in the art byproviding a surgical needle with a weeping tip for microinjection ofmedicaments into a body surface. The invention surgical needle comprisesa nonporous hollow needle shaft having a proximal end adapted to matewith a surgical instrument, a porous distal portion in fluid-tightconnection to the needle shaft, and a point that is open, closed, or hasa solid partial plug. The distal portion of the invention needle isadapted to cause a liquid injectate to weep or ooze therefrommultidirectionally under injection pressure while the distal portion andpoint of the needle are inserted into a body surface. Typically, thelength of the porous distal portion of the needle is determined by itsintended use (e.g., whether intended for injecting medicament into ablood vessel or into a kidney, and the like). However, the porous distalportion is generally about 1 mm to about 20 mm in length and has poreswith an average largest dimension in the range from about 1.0 micron toabout 200 microns, for example, in the range from about 3 microns toabout 100 microns, or from about 5 microns to about 75 microns.

The invention surgical needle with weeping tip can be adapted forattachment to such surgical instruments as a syringe, but is preferablyadapted for attachment to the distal tip of a nonporous catheter. Theassemblage of the needle and catheter is preferably steerable. Forexample, the needle can be attached to the distal tip of a steerablecatheter (i.e., comprising a steering mechanism at the handle forcontrolling deflection of the distal tip section of the catheter shaft),such as is known in the art for injection of medicaments into a remotebody cavity or organ wall. Alternatively, the needle can be attached toa catheter with a porous distal portion and then the combination can beintroduced into a steerable guidance catheter, such as is used in suchsurgical techniques as angioplasty, transmyocardial revascularization(TMR), percutaneous tnnnsmyocardial revascularization (PTMR), and thelike, to direct the needle and catheter to the appropriate site forinjection of a medicament Guidance catheters suitable for use in theinvention assemblages and methods are commercially available, forexample from such vendors as Eclipse Surgical Technologies (Sunnyvale,Calif.) and CardioGenesis Corp. (Sunnyvale, Calif.).

In one embodiment according to the present invention, the surgicalneedle is fabricated from a metal commonly used to make surgicalneedles, such as stainless steel, nitinol, tantalum, elgiloy, and thelike, and provided with a distal portion having a multiplicity of pores,while the proximal portion of the needle (i.e., the nonporous hollowneedle shaft) is fluid-tight to prevent leakage of fluid therefrom.Consequently, in use it is important to insert the complete porousdistal portion of the needle into tissue before and during injection ofa medicament.

In another embodiment according to the present invention, the porousdistal portion of the surgical needle is adapted to create decreasinghydraulic impedance on injectate moving therethrough towards the pointto cause a substantially uniform rate of weeping of injectate from theporous distal portion along the length thereof. The decrease inhydraulic impedance can be of any type, for example, linear,exponential, Gaussian, and the like, and with a gradient in eitherlongitudinal direction.

For example, to create decreasing hydraulic impedance along the lengthof the porous portion, the size and/or number of the pores in the porousdistal portion can increase along its length from the proximal endtowards the point. Adjustment of the porosity along the length of theporous distal portion may also be in conjunction with an increasinginterior diameter along the length of the porous portion from theproximal end towards the point as needed to offset a falling off ofinjection pressure on fluid exiting towards the distal end of thedevice. Alternatively, if a different gradient of injectate is desired,the pore number and/or size can be arranged in any direction suitable toaccomplish such a gradient.

The sharp point of the invention needle can be open, closed, or fittedwith a solid partial plug to prevent the injectate from exiting as asingle jet. If the point of the needle is open, the rate of flow fromthe open point can also be controlled by adjustment of the hydraulicimpedance along the length of the distal portion of the needle toprevent the rate of fluid flow at the tip from substantially exceedingthe rate of fluid flow along the porous portion adjacent to the point ofthe needle.

Alternatively, the point of the needle can be open, but restricted by asolid partial plug so that the distal tip of the needle is designed tooperate similarly to the tip of a garden nozzle wherein the solidpartial plug cooperates with the open tip to restrict exit of fluid,thereby preventing exit of the fluid as a single jet.

In another embodiment wherein the needle has an open tip, the tip (and adistal portion of the needle shaft) can be loosely covered or looselysheathed with a porous material, such as the porous sintered metal meshdescribed above to create the porous distal portion of the needle. Inthis embodiment, the sheath is attached (e.g., fused or welded) to theneedle shaft to create the porous portion from which injectate will weepor ooze (i.e., from the pores in the porous sheath).

The proximal end of the invention needle shaft is provided with aconnector, such as a flange, hub, or the like, as is known in the art,for removable attachment of the needle to a surgical instrument, such asa syringe or a catheter. The surgical instrument serves as a reservoirfor the fluid medicament. Therefore, the connector is such that there isfluid communication between the needle and the surgical instrument. Inuse, the invention needle is mounted on the distal tip of the surgicalinstrument, which is adapted to apply or transmit pressure to themedicament within the nonporous hollow shaft of the needle.

The distal portion of the needle can be fabricated from any of a numberof different “open cell” porous materials (i.e., materials in which thepores are interconnecting). For example, the distal portion can befabricated from a porous sintered metal, such as forms a non-wovenmatrix of metal fibers selected from such metals as stainless steel,tantalum, elgiloy, nitinol, and the like, and suitable combinations ofany two or more thereof. Generally, the metal fibers will have adiameter in the range from about 1.0 micron to about 25 microns. Anon-woven matrix of metal fibers having these desired properties thatcan be used in manufacture of the porous distal portion of the inventionneedle is available from the Bekaeart Corporation (Marietta, Ga.), andis sold under the trademark, BEKIPOR® filter medium.

The distal porous portion of the needle can also be fabricated from suchporous materials as a porous polymer, such as a porous polyimide,polyethylene, polypropylene, polytetrafluoroethylene, and the like. Suchporous polymers are disclosed, for example, in U.S. Pat. No. 5,913,856,which is incorporated herein by reference in its entirety.Alternatively, a porous ceramic can be used, such as is known in the artfor use in ceramic filters and separation membranes, or a porous metal(also known as an expanded metal) or carbon, such as is known in the artfor use in filters or bone grafts. For example, Mott Corporation(Farmington, Conn.) manufactures porous metals for use in various typesof filters.

If the porous filter medium is flexible, the distal portion of theinvention needle can be fabricated by wrapping the filter medium, whichis available commercially as a flat sheet, one or more times around anaxis while creating a hollow central core. The porous distal portion ofthe needle can then be fused in fluid-tight fashion (e.g. welded) to anon-porous hollow needle shaft using methods known in the art. To createa porous portion of the needle having decreasing impedance to fluidflow, a porous filter medium or metal mesh having an appropriateporosity gradient can be employed in fabrication of the porous portion.

Alternatively, a porous distal portion for the invention needle can becreated from a non-porous material (e.g., a metal) using a cutting laserand techniques known in the art to punch pores into the needle segment(i.e. by a process of laser etching). For example, the nonporous hollowshaft porous portion, and point of the invention needle can befabricated of metal in a single piece, for example, from a conventionalhypotube. In this scenario, a metal-cutting laser is used to create asegment of the needle that has appropriate porosity, for example, aporosity gradient within a portion of the needle as disclosed herein toequalize fluid impedance along the length of the porous portion of theneedle.

In any event, the porosity of the distal portion is generally in therange from about 50% to about 85%, for example, at least about 70%.

Thus, the multidirectional flow of medicament from the needle iscontrolled by a number of factors, for example, the size, multiplicityand arrangement of the pores in the distal portion, the viscosity of theliquid medicament, the pressure applied to the medicament via thesurgical instrument to which it is attached (i.e., the “injectionpressure”), and the like. Those of skill in the art will know how toselect and combine these factors to assure that the medicament weepsmultidirectionally from the pores in the distal portion of the needleinto tissue into which it is inserted without substantial surfaceleakage or tissue damage attributable to the injectate. For example, bybalancing these factors, the flow of a liquid medicament from the needlecan be adjusted to be at a rate slow enough for the injectate to beabsorbed into tissue in the injection site without substantialdisruption of cellular and membrane structures as would be caused bybolus or rapid injection, especially from a needle having a singleopening. A rate of injection in the range from about 0.1 cc per secondto about 2.0 cc per second, for example, from about 0.5 cc per second toabout 1.0 cc per second is generally suitable to accomplish these goals.

In the embodiment of the invention illustrated in FIG. 1 herein, needle2 has a nonporous hollow needle shaft, a porous distal portion 6 havinginter-connecting pores and a closed sharp tip 8. Injectate 12 oozes fromthe pores in the distal portion under injection pressure. The sharp tip8 of needle 2 is closed so that no injectate flows from the point of theneedle. The proximal end of needle 2 is fitted with flange 10 forremovable attachment to a catheter. The distal end of catheter 16, whichhas at least one open lumen 14 for passage of injectate into needle 2attaches to the proximal end of needle 2. In other embodiments, a hubfor mating with a syringe is substituted for the flange at the proximalend of the needle.

In another embodiment according to the present invention, the inventionneedle further comprises one or more sensor connectors for electricalattachment to an electrocardiogram. The electrocardiogram can be used todetermine contact between the needle tip and the tissue, or if multipleelectrodes are present, to determine the depth of penetration. In theembodiment shown in FIG. 2, the exterior of the needle shaft (notvisible in this Figure) is coated with an insulator 18 and the connector19 is attached directly to the proximal end (uncoated) of the needleshaft. Electrical lead 20 can be threaded down the lumen of a catheterfor attachment to an electrocardiogram. Multiple leads can also be usedin order to determine depth of the needle. In this configuration, theelectrocardiogram is recorded from all leads. The larger signal ispresent from those ECG leads that are intramyocardial. Alternatively,the connector can be attached to the interior of the tip of the needlewith an insulated connecting wire running down the hollow interior ofthe needle and catheter for attachment to an electrocardiogram. In thisembodiment the needle itself acts as the electrode for theelectrocardiogram and can be used for monopolar sensing of electricalcurrents or impedance within the heart, brain, nerves, proximalarteries, and the like.

For bipolar sensing a return electrode can be provided by placing an ECGpad in electrical connection with the electrocardiogram on the exteriorof the patient, for example on the exterior of the chest wall. It isalso contemplated within the scope of the invention that a secondelectrode or sensor connector can be attached to the needle, for exampleto the exterior of the needle, spaced apart from the first electrode byat least about 0.5 mm, so as to provide two electrodes for sensingelectrical currents within a subject's bodily organs. It is alsopossible that an electrode permanently implanted in a subject, such asbelongs to a pacemaker, can be used as the return lead for remotebipolar sensing.

The advantages of using the invention needles to perform sensing areseveral. For example, for injection into a muscle or other organ thathas electrical impulses running through it, an electrocardiogram sensorattached to the invention needle can be used to confirm contact of theneedle tip or proper insertion of the needle into the body wall ofinterest (e.g., the wall of a beating heart) before injection of themedicament into a treatment site. The depth of needle insertion into thetissue is determined by an array of electrodes. Those of skill in theart will realize that the invention needle having attachedelectrocardiogram sensor can also be used to judge whether such aprospective injection site is electrically active or not (i.e., whetherthe tissue is dead, hibernating due to lack of oxygen, or alive), andthe like.

In another embodiment according to the present invention, there areprovided surgical assemblages useful for microinjection of a liquidmedicament into a remote location in a subject in need thereof. Theinvention surgical assemblage comprises a needle with a sharp distalpoint, and a catheter with a porous distal portion attached to thedistal end of the needle, wherein the porous distal portion is adaptedto cause a liquid injectate to weep or ooze multidirectionally therefrominto surrounding tissue under injection pressure while the porous distalportion of the catheter is inserted into a body surface. The catheter inthe invention surgical assemblage can be a steerable catheter having asteering mechanism at the handle for controlling deflection of thedistal tip section of the catheter shaft, thereby, in effect, creating a“steerable needle.”

Alternatively, the invention surgical assemblage can further comprise aguidance catheter of the type known in the art for guiding instrumentsused in angioplasty, as is described more fully hereinabove. In thisembodiment, the needle and catheter with porous distal portion isintroduced into (i.e., threaded through) the guidance catheter so thatthe needle and catheter with porous distal portion can be directed tothe site of injection (e.g., threaded through a desired section oftissue) using the steerable guidance catheter.

Preferably, the porous distal portion of the catheter is made of aflexible porous polymer, such as a porous polyimide, polyethylene,polytetrafluoroethylene, or polypropylene, and the like. The porousdistal portion may further have features that create increasinghydraulic impedance on injectate moving therethrough towards the needle,thereby causing uniform flow of the injectate therefrom along the lengthof the porous distal portion as the injectate moves therethrough towardsthe needle to offset the falling off of injection pressure on fluid asit moves towards the point of the device. The flexibility of the poroussegment in the assemblage facilitates injection of medicaments along anon-linear path.

As with the porous portion of the invention surgical needle describedabove, the size, and/or number of pores in the porous portion of thecatheter in the invention surgical assemblage can be selected to createany desired gradient of injectate along the course of the injectionpath. For example, the size, and/or number of pores can decrease alongthe length of the porous portion moving towards the connection with theneedle to allow for a substantially uniform rate of injectate weepagealong the length of the porous portion. In this configuration,therefore, once the needle is used to thread the porous portion of thecatheter through the tissue to be treated, a substantially uniform rateof fluid weepage into surrounding tissues can be obtained along theinjection course. Alternatively, or in conjunction with such a porositygradient, the porous distal portion can also have a decreasing interiordiameter along its length moving from the proximal end towards theconnection with the needle to accomplish the same goal.

FIG. 3 herein illustrates the invention surgical assemblage 22.Non-porous needle 24 with a closed tip is attached to the distal end offlexible catheter 26, which has a porous distal portion 28. Injectate 30weeps from the pores in the flexible distal portion 28 of catheter 26.

In another embodiment according to the present invention, there areprovided methods for injecting a medicament into an body wall in asubject in need thereof. The invention method comprises inserting theporous distal portion of the invention needle into the tissue of thesubject and applying sufficient injection pressure to a liquidmedicament in fluid communication with the porous distal portion of theneedle to cause the medicament to ooze multidirectionally from the poresin the needle into the tissue. Alternatively, the invention surgicalassembly, wherein the porous portion is not contained in the needle, butis a porous distal portion of an otherwise nonporous catheter, can beused in the invention injection methods to similar effect. If the pointand porous portion of the needle or surgical assembly are inserted intothe tissue before the medicament is injected, the injection ofmedicament is performed without substantial leakage or loss ofmedicament at the surface of the tissue or interior body wall.

As used herein, the term “medicament(s)” includes all types of liquidsubstances (e.g., including solutions and suspensions) that have abeneficial or therapeutic effect. Non-limiting examples of medicamentssuitable for use in the invention methods include biologically activeagents, such as small molecule drugs, proteinaceous substances,polynucleotides or nucleic acids (e.g. heterologous DNA, or RNA) andvectors, liposomes, and the like, containing such nucleic acids orpolynucleotides, as well as liquid preparations or formulations thereof.

The invention methods and devices are designed for injection of minuteamounts of fluid medicaments into tissue or a body wall, for example, aninterior body wall. Hence the use of the term “microinjection” herein.For example, the therapeutic amount of the medicament to be administeredaccording to the invention method will vary depending upon thetherapeutic goal to be accomplished, the size and age of the subject,the pharmacokinetics of the injectate, and the like. However, atherapeutic amount according to the present invention is typically inthe range from about 0.5 cc to about 2.0 cc.

Under injection pressure exerted upon a fluid medicament within theinvention needle or surgical assemblage, the injectate will weep or oozemultidirectionally from the porous distal portion into surroundingtissue into which it is inserted, but should be prevented from exitingfrom the proximal portions of the invention devices. Flow of theinjectate into the surrounding tissue is contemplated to be at a slowrate, for example, in the range from about 0.1 cc per second to about2.0 cc per second to allow absorption of and dissipation the medicamentinto the tissue without substantial tissue damage caused by theinjectate, (e.g., pooling of the medicament is thereby avoided). So longas the injectate contains no particles (e.g. cells) larger than thepores in the distal portion of the needle, overall flow of themedicament into tissue will be proportional to the amount of pressureapplied on the injectate.

However, unless the porous portion of the invention device is adapted tocause a increasing gradient of impedance to fluid flow as the fluidmoves distally through the porous portion (i.e., towards the point ofthe needle), the medicament will not weep at a uniform flow rate alongthe length of the porous portion.

In practice of the invention methods, it is presently preferred that thecombination of the needle and the surgical instrument to which it isattached be selected so that the amount of the medicament that oozesfrom the pores of the needle can be controlled by the operator. Forexample, if a measured amount of the medicament is placed for deliveryinto a calibrated chamber of the surgical instrument and/or hollow ofthe needle, pressure on the medicament in the chamber sufficient todeliver 2 cc of the medicament from the pores of the distal portion ofthe needle while the distal portion is inserted into tissue of thesubject will substantially assure that the subject receives 2 cc of themedicament This feature of the invention devices and methods isparticularly advantageous when it is important to closely monitor theamount of the medicament delivered to the subject, for example, to avoidwaste of the medicament, to accurately judge the efficacy of thetreatment, and the like.

The invention methods can be used to deliver to a subject in need ofgene therapy an therapeutic amount of a medicament containing anisolated therapeutic nucleic acid sequence, or a vector, liposome, orcell, and the like, containing such a nucleic acid sequence operativelyassociated with regulatory nucleic acid for expression of the encodedtherapeutic protein. The invention devices and methods can be used topromote gene therapy by injection of such medicaments even when theinjection site is located internally and/or is in constant motion.Therefore, in another embodiment according to the present invention,there are provided methods for injecting a therapeutic amount of amedicament into an interior body wall or tissue of a subject in needthereof. In this embodiment, the invention method comprises insertingthe distal portion of the invention needle into an interior body wall ortissue of the subject and applying sufficient pressure to a liquidmedicament in fluid communication with the distal portion of the needleto expel a therapeutic amount of the medicament such that the medicamentweeps multidirectionally from the pores in the distal portion thereofinto the interior body wall or tissue without substantial leakage orloss of the medicament at the surface of the body wall. The body wallcan be located within a natural body cavity or a surgically createdopening.

The invention method utilizing the needle with weeping tip isparticularly useful for injection of medicaments into the wall of aninterior organ that is subject to motion during the injection procedure,for example, the wall of a beating heart or adjacent arterial wallsduring electrophysiologic testing, transmyocardial revascularization,and the like. Additional internal organs subject to movement into whichinjections can be made using the invention methods include the stomach,esophagus, gallbladder, liver, bowel, kidney, lung, and the like.

By “isolated polynucleotide” or “isolated nucleic acid” or isolatednucleic acid sequence” is meant a polynucleotide that is not immediatelycontiguous with both of the coding sequences with which it isimmediately contiguous (one on the 5′ end and one on the 3′ end) in thenaturally occurring genome of the organism from which it is derived. Theterm therefore includes, for example, a recombinant DNA which isincorporated into a vector; into an autonomously replicating plasmid orvirus; or into the genomic DNA of a prokaryote or eukaryote; or whichexists as a separate molecule (e.g. a cDNA) independent of othersequences. Therapeutic nucleic acids contemplated for use in thepractice of the present invention are intended to include those whichencode products which are toxic to the cells in which they areexpressed; those that encode products which impart a beneficial propertyto a subject; and those that transcribe nucleic acids which modulatetranscription and/or translation of endogenous genes.

Preferred examples of suitable therapeutic nucleic acids foradministration into cardiac tissues using the invention devices andmethods include those encoding growth factors that enhance apoptosis andcell growth, such as bFGF (basic fibroblast growth factor, also known asFGF-2), AFGF (also known as FGF-1), EGF (epithelial growth factor), VEGF(vascular epithelial growth factor), angiostatin, ecchystatin, IGFs(insulin-like growth factors), and the like. These agents can be used toenhance or prevent the development of new blood vessels, preventinflammation (as results from direct injection into the wall of anartery), prevent neointimal hyperplasia, or enhance or prevent thegrowth of new myocardial cells.

Additional therapeutic nucleic acids useful in the practice of thepresent invention include genes that encode biologically active proteinsof interest, such as, e.g., secretory proteins that can be released fromsaid cell; enzymes that can metabolize a toxic substance to produce anon-toxic substance, or that metabolize an inactive substance to producea useful substance; regulatory proteins; cell surface receptors; and thelike. Useful genes include genes that encode blood clotting factors,such as human factors VIII and IX; genes that encode hormones, such asinsulin, parathyroid hormone, luteinizing hormone releasing factor(LHRH), alpha and beta seminal inhibins, and human growth hormone; genesthat encode proteins, such as enzymes, the absence of which leads to theoccurrence of an abnormal state; genes encoding cytokines or lymphokinessuch as interferons, granulocytic macrophage colony stimulating factor(GM-CSF), colony stimulating factor-1 (CSF-1), tumor necrosis factor(TNF), and erytropoietin (EPO); genes encoding inhibitor substances suchas alpha₁-antitrypsin; genes encoding substances that function as drugs,e.g., genes encoding the diphtheria and cholera toxins; and the like.

Typically, nucleic acid sequence information for proteins encoded bytherapeutic nucleic acid(s) contemplated for use employed herein can belocated in one of many public access databases, e.g., GENBANK, EMBL,Swiss-Prot, and PIR, or in related journal publications. Thus, those ofskill in the art have access to sequence information for virtually allknown genes. Those of skill in the art can obtain the correspondingnucleic acid molecule directly from a public depository or from theinstitution that published the sequence. Optionally, once the nucleicacid sequence encoding a desired protein has been ascertained, theskilled artisan can employ routine methods, e.g., polymerase chainreaction (PCR) amplification, to isolate the desired nucleic acidmolecule from the appropriate nucleic acid library. Thus, all knownnucleic acids encoding proteins of interest are available for use in themethods and products described herein.

Additional components that can optionally be incorporated into theinvention constructs include selectable markers and genes encodingproteins required for retroviral packaging, e.g., the pol gene, the gaggene, the env gene, and the like.

Selectable markers contemplated for use in the practice of the presentinvention include antibiotic resistance genes, genes that enable cellsto process metabolic intermediaries, and the like. Exemplary antibioticresistance genes include genes which impart tetracycline resistance,genes that impart ampicillin resistance, neomycin resistance, hygromycinresistance, puromycin resistance, and the like.

Optionally, the cells can be obtained from the subject or host (i.e.,rather than a donor), modified as above, and then reintroduced into thesubject using the invention devices and methods. For example,therapeutic nucleic acid can be introduced directly into cells obtainedfrom a subject and the modified cells can be then injected into thesubject. The therapeutic nucleic acid may be stably incorporated intocells or may be transiently expressed using methods known in the art.

Modified cells are cultivated under growth conditions (as opposed toprotein expression conditions) until a desired density is achieved.Stably transfected mammalian cells may be prepared by transfecting cellswith an expression vector having a selectable marker gene (such as, forexample, the gene for thymidine kinase, dihydrofolate reductase,neomycin resistance, and the like), and growing the transfected cellsunder conditions selective for cells expressing the marker gene. Toprepare transient transfectants, mammalian cells are transfected with areporter gene (such as the E. coli β-galactosidase gene) to monitortransfection efficiency. Selectable marker genes are typically notincluded in the transient transfections because the transfectants aretypically not grown under selective conditions, and are usually analyzedwithin a few days after transfection.

The concept of gene replacement therapy for humans involves theintroduction of functionally active nucleic acids into the somatic cellsof an affected subject to correct a gene defect or deficiency. Genesthat encode useful “gene therapy” proteins that are not normallytransported outside the cell can be used in the invention if such genesare “functionally appended” to, or operatively associated with, a signalsequence that can “transport” the encoded product across the cellmembrane. A variety of such signal sequences are known and can be usedby those skilled in the art without undue experimentation.

Regulatory elements employed in the practice of the present inventionare operably linked to a suitable promoter for transcription oftherapeutic nucleic acid product(s). As used herein, the term “promoter”refers to a specific nucleic acid sequence recognized by RNA polymerase,the enzyme that initiates RNA synthesis. The promoter sequence is thesite at which transcription can be specifically initiated under properconditions. When exogenous nucleic acid(s), operatively linked to asuitable promoter, are introduced into the cells of a suitable host,expression of the exogenous nucleic acid(s) can be controlled in many,but not all cases, by the presence of ligands, which are not normallypresent in the host cells.

Promoters contemplated for control of expression of exogenous nucleicacids employed in the practice of the present invention includeinducible (e.g., minimal CMV promoter, minimal TK promoter, modifiedMMLV LTR), constitutive (e.g., chicken β-actin promoter, MMLV LTR(non-modified), DHFR), and/or tissue specific promoters.

Inducible promoters contemplated for use in the practice of the presentinvention comprise transcription regulatory regions that functionmaximally to promote transcription of mRNA under inducing conditions.Examples of suitable inducible promoters include DNA sequencescorresponding to: the E. coli lac operator responsive to IPTG (seeNakamura et al., Cell, 18:1109-1117, 1979); the metallothionein promotermetal-regulatory-elements responsive to heavy-metal (e.g., zinc)induction (see Evans et al., U.S. Pat. No. 4,870,009), the phage T7lacpromoter responsive to IPTG (see Studier et al., Meth Enzymol., 185:60-89, 1990; and U.S. Pat. No. 4,952,496), the heat-shock promoter; theTK minimal promoter, the CMV minimal promoter; a synthetic promoter, andthe like.

Exemplary constitutive promoters contemplated for use in the practice ofthe present invention include the CMV promoter, the SV40 promoter, theDHFR promoter, the mouse mammary tumor virus MMTV steroid-induciblepromoter, Moloney murine leukemia virus (MMLV) promoter, elongationfactor 1a (EF1a) promoter, albumin promoter, APO A1 promoter, cyclic AMPdependent kinase II (CaMKII) promoter, keratin promoter, CD3 promoter,immunoglobulin light or heavy chain promoters, neurofiliment promoter,neuron specific enolase promoter, L7 promoter, CD2 promoter, myosinlight chain kinase promoter, HOX gene promoter, thymidine kinase (TK)promoter, RNA Pol II promoter, MYOD promoter, MYF5 promoter,phosphoglycerokinase (PGK) promoter, Stf1 promoter, Low DensityLipoprotein (LDL) promoter, chicken β-actin promoter (e.g., used inconjunction with an ecdysone response element), and the like.

As readily understood by those of skill in the art, the term “tissuespecific” refers to the substantially exclusive initiation oftranscription in the tissue from which a particular promoter that drivesexpression of a given gene is derived (e.g., expressed only in T-cells,endothelial cells, smooth muscle cells, and the like). Exemplary tissuespecific promoters contemplated for use in the practice of the presentinvention include the GH promoter, the NSE promoter, the GFAP promoter,neurotransmitter promoters (e.g., tyrosine hydroxylase, TH, cholineacetyltransferase, ChAT, and the like), promoters for neurotropicfactors (e.g., a nerve growth factor promoter, NT-3, BDNF promoters, andthe like), and so on.

As used herein, the phrase “operatively associated with” refers to thefunctional relationship of DNA with regulatory and effector sequences ofnucleic acids, such as promoters, enhancers, transcriptional andtranslational stop sites, and other signal sequences. For example,operative linkage of DNA to a promoter refers to the physical andfunctional relationship between the DNA and promoter such that thetranscription of such DNA is initiated from the promoter by an RNApolymerase that specifically recognizes, binds to and transcribes theDNA.

Gene transfer vectors (also referred to as “expression vectors”)contemplated for use herein are recombinant nucleic acid molecules thatare used to transport nucleic acid into host cells for expression and/orreplication thereof Expression vectors may be either circular or linear,and are capable of incorporating a variety of nucleic acid constructstherein. Expression vectors typically come in the form of a plasmidthat, upon introduction into an appropriate host cell, results inexpression of the inserted nucleic acid.

Suitable expression vectors for use herein are well known to those ofskill in the art and include recombinant DNA or RNA construct(s), suchas plasmids, phage, recombinant virus or other vectors that, uponintroduction into an appropriate host cell, result(s) in expression ofthe inserted DNA. Appropriate expression vectors are well known to thoseof skill in the art and include those that are replicable in eukaryoticcells and/or prokaryotic cells and those that remain episomal or thosewhich integrate into the host cell genome. Expression vectors typicallyfurther contain other functionally important nucleic acid sequencesencoding antibiotic resistance proteins, and the like.

The amount of therapeutic nucleic acid introduced into a subject can bevaried by those of skill in the art. For example, when a viral vector isemployed to achieve gene transfer, the amount of nucleic acid introducedcan be varied by varying the amount of plaque forming units (PFU) of theviral vector.

Exemplary eukaryotic expression vectors include eukaryotic constructs,such as the pSV-2 gpt system (Mulligan et al., Nature 277:108-114,1979); pBlueSkript (Stratagene, La Jolla, Calif.), the expressioncloning vector described by Genetics Institute (Science 228:810-815,1985), and the like. Each of these plasmid vectors is capable ofpromoting expression of the protein product of the nucleic acid ofinterest.

Suitable means for introducing (transducing) expression vectorscontaining therapeutic nucleic acid constructs into cells of a subjecttreated according to the invention methods include infection employingviral vectors (see, e.g., U.S. Pat. No. 4,405,712 and 4,650,764). Thetransduced nucleic acid can optionally include sequences which allow forits extrachromosomal (i.e., episomal) maintenance, or the transducednucleic acid can be donor nucleic acid that integrates into the genomeof the host.

In a specific embodiment, a gene transfer vector contemplated for useherein is a viral vector, such as Adenovirus, adeno-associated virus, aherpes-simplex virus based vector, a synthetic vector for gene therapy,and the like (see, e.g., Suhr et al., Arch of Neurol. 50:1252-1268,1993). Preferably, a gene transfer vector employed herein is aretroviral vector. Retroviral vectors contemplated for use herein aregene transfer plasmids that have an expression construct containing anexogenous nucleic acid residing between two retroviral LTRs. Retroviralvectors typically contain appropriate packaging signals that enable theretroviral vector, or RNA transcribed using the retroviral vector as atemplate, to be packaged into a viral virion in an appropriate packagingcell line (see, e.g., U.S. Pat. No. 4,650,764).

Suitable retroviral vectors for use herein are described, for example,in U.S. Pat. No. 5,399,346 and 5,252,479; and in WIPO publications WO92/07573, WO 90/06997, WO 89/05345, WO 92/05266 and WO 92/14829, each ofwhich is hereby incorporated herein by reference, in its entirety. Thesedocuments provide a description of methods for efficiently introducingnucleic acids into human cells using such retroviral vectors. Otherretroviral vectors include, for example, mouse mammary tumor virusvectors (e.g., Shackleford et al PNAS, USA, 85:9655-9659, 1988), humanimmunodeficiency virus (e.g., Naldini et al. Science 272:165-320, 1996),and the like.

Various procedures are also well-known in the art for providing helpercells which produce retroviral vector particles that are essentiallyfree of replicating virus. See, for example, U.S. Pat. No. 4,650,764;Miller, Human Gene Therapy, 1:5-14, 1990; Markowitz, et al., Journal ofVirology, 61(4): 1120-1124, 1988; Watanabe, et al., Molecular andCellular Biology, 3(12):2241-2249, 1983; Danos, et al., PNAS,85:6460-6464, 1988; and Bosselman, et al., Molecular and CellularBiology, 7(5):1797-1806, 1987, which disclose procedures for producingviral vectors and helper cells that minimize the chances for producing aviral vector that includes a replicating virus.

Recombinant retroviruses suitable for carrying out the invention methodsare produced employing well-known methods for producing retroviralvirions. See, for example, U.S. Pat. No. 4,650,764; Miller, supra 1990;Markowitz, et al., supra 1988; Watanabe, et al., supra 1983; Danos, etal., PNAS, 85:6460-6464, 1988; and Bosselman, et al., Molecular andCellular Biology, 7(5):1797-1806, 1987.

By introducing all of the necessary regulatory machinery, plus exogenousnucleic acid, selectable markers, and nucleic acid encoding inventionchimeric protein, e.g., into a MARV retrovirus, highly efficientinsertion of exogenous nucleic acids into targeted cells can beachieved.

Thus, the above-described viral constructs address several importantproblems confronted in the use of retroviruses in application oftherapeutic gene transfer strategies to a variety of human diseases. Forexample, the retroviral vectors of the invention are capable ofprolonged gene expression under conditions where conventionallyintegrated retroviruses are no longer transcriptionally active.

As used herein, when referring to nucleic acids, the phrase “exogenousto said mammalian host” or simply “exogenous” refers to nucleic acidsnot naturally found at levels sufficient to provide a function in theparticular cell where transcription is desired. For example, exogenousnucleic acids can be either natural or synthetic nucleic acids, whichare introduced into the subject in the form of DNA or RNA, The nucleicacids of interest can be introduced directly or indirectly into asubject, for example, by the transfer of transformed cells into asubject using invention methods.

As employed herein, the terms “subject” and “host” refer to a mammalianpatient in need of administration of a medicament. The subject mammalsinclude: humans; domesticated animals, e.g., rat, mouse, rabbit, canine,feline, and the like; farm animals, e.g., chicken, bovine, ovine,porcine, and the like; animals of zoological interest, e.g., monkey,baboon, and the like.

While the invention has been described in detail with reference tocertain preferred embodiments thereof, it will be understood thatmodifications and variations are within the spirit and scope of thatwhich is described and claimed.

What is claimed is:
 1. A surgical assemblage comprising: a hypodermicneedle with a sharp distal point that is open, closed, or has a solidpartial plug, and a catheter with a porous distal portion attached tothe proximal end of the needle, wherein a gradient in the size ordistribution of the pores and/or interior diameter of the porous distalportion causes a gradient of hydraulic impedance on a liquid injectatemoving therethrough and wherein the pores are sized to cause theinjectate to weep or ooze multidirectionally therefrom into surroundingtissue under injection pressure while inserted into a body surface. 2.The assemblage according to claim 1 wherein the porous distal portioncreates a gradient of hydraulic impedance on injectate movingtherethrough in order to preferentially deliver agent at anylongitudinal point longitudinally along the distal portion.
 3. Theassemblage according to claim 2 wherein the decrease in impedance islinear, exponential or Gaussian.
 4. The assemblage according to claim 1wherein the needle has a length in the range from about 100 mm to about1500 mm and the porous distal portion of the catheter has a length inthe range from about 1 mm to about 20 mm.
 5. The assemblage according toclaim 1 wherein the porous distal portion is made of a porous polymer.6. A surgical assemblage comprising: a nonporous needle with a sharpdistal point, said needle being adapted at a proximal end for attachmentto a distal end of a catheter, and a catheter comprising a porous distalportion and a distal end that is adapted for attachment to the needle,wherein a gradient in the size or distribution of the pores and/orinterior diameter of the porous distal portion causes a gradient ofhydraulic impedance on a liquid injectate moving therethrough andwherein the pores are sized to cause the injectate to weep or oozemultidirectionally therefrom into surrounding tissue under injectionpressure while the porous distal portion of the catheter is insertedinto a body surface.
 7. The assemblage according to claim 6 wherein theneedle has a length in the range from about 10 mm to about 1500 mm andthe porous distal portion has a length in the range from about 1 mm toabout 20 mm.
 8. The assemblage according to claim 6 wherein the catheteris a steerable catheter.
 9. The assemblage according to claim 6 furthercomprising a guidance catheter for receiving and steering the assembledneedle and catheter with a porous distal portion to an injection site.10. A method for preventing substantial tissue damage when injecting amedicament, said method comprising: injecting the medicament from aporous distal portion of a catheter of claim 6 into the subject so thatthe medicament weeps multidirectionally from pores in the distal portionthereof without substantial damage to tissue of the subject caused byinjectate.
 11. The surgical assemblage of claim 1 wherein said surgicalassemblage is adapted to weep or ooze a liquid injectate which is amedicament.
 12. The surgical assemblage of claim 11 wherein saidmedicament contains nucleic acid encoding a therapeutic agent.
 13. Thesurgical assemblage of claim 1 further including a syringe having adistal end attached to a proximal end of the catheter.
 14. The surgicalassemblage of claim 1 wherein said sharp distal point that is open isloosely covered with a porous material.
 15. The surgical assemblage ofclaim 6 wherein said needle and catheter are steerable.
 16. The surgicalassemblage of claim 6 wherein said catheter serves as a reservoir forthe injectate.
 17. The surgical assemblage of claim 6 wherein saidporous distal portion of said catheter is flexible.
 18. The method ofclaim 10 further comprising determining a depth of needle penetrationusing one or more sensor connectors in electrical attachment to saidneedle and an electrocardiogram.
 19. The method of claim 10 furthercomprising adjusting a flow rate of said medicament to expel atherapeutic amount of said medicament without substantial loss of saidmedicament at a surface of a body wall of said subject.
 20. The methodof claim 10 further comprising supplying sufficient pressure to saidmedicament to expel a therapeutic amount of said medicament into amoving, interior organ of said subject.